U.S. patent application number 09/991023 was filed with the patent office on 2002-10-31 for turbine power unit for hybrid electric vehicle applications.
Invention is credited to Bakholdin, Daniel, Geis, Everett, Gilbreth, Mark, Wacknov, Joel.
Application Number | 20020157881 09/991023 |
Document ID | / |
Family ID | 26939100 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020157881 |
Kind Code |
A1 |
Bakholdin, Daniel ; et
al. |
October 31, 2002 |
Turbine power unit for hybrid electric vehicle applications
Abstract
A power generation system for a hybrid electric vehicle is
disclosed. The system includes a fuel source, a turbogenerator
coupled to the fuel source, and a power controller. The power
controller is electrically coupled to the turbogenerator, and
includes first and second power converters. The first power
converter converts AC power from the turbogenerator to DC power on
a DC bus, and the second power converter converts the DC power on
the DC bus to an operating DC power on output lines. The power
controller regulates the fuel to the turbogenerator, independent of
DC voltage on the DC bus. The system further includes an electric
motor, a drive control unit coupled between the output lines and
the electric motor, and a traction battery. The traction battery is
coupled across the output lines, and provides an additional source
of current, upon demand, to the electric motor.
Inventors: |
Bakholdin, Daniel; (Canyon
Country, CA) ; Geis, Everett; (Orange, CA) ;
Wacknov, Joel; (Thousand Oaks, CA) ; Gilbreth,
Mark; (Simi Valley, CA) |
Correspondence
Address: |
IRELL & MANELLA LLP
840 NEWPORT CENTER DRIVE
SUITE 400
NEWPORT BEACH
CA
92660
US
|
Family ID: |
26939100 |
Appl. No.: |
09/991023 |
Filed: |
November 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60248090 |
Nov 13, 2000 |
|
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|
Current U.S.
Class: |
180/65.245 ;
903/905 |
Current CPC
Class: |
B60W 2510/0676 20130101;
B60W 2050/001 20130101; B60W 10/08 20130101; B60K 6/46 20130101;
Y02T 10/62 20130101; B60K 6/24 20130101; B60L 2240/445 20130101;
B60W 2710/0616 20130101; B60W 2710/06 20130101 |
Class at
Publication: |
180/65.2 |
International
Class: |
B60K 006/00 |
Claims
What is claimed is:
1. A power generation system for a hybrid electric vehicle,
comprising: a fuel source to provide fuel; a turbogenerator,
coupled to the fuel source, to generate AC power; a power
controller, electrically coupled to the turbogenerator, including
first and second power converters, said first power converter to
convert said AC power to a DC voltage on a DC bus, and said second
power converter to convert said DC voltage on said DC bus to an
operating DC voltage on output lines, said power controller to
regulate the fuel to the turbogenerator, independent of the DC
voltage on the DC bus; an electric motor; a drive control unit
coupled between the output lines and the electric motor, said drive
control unit, under control of the power controller, to couple or
isolate the electric motor to or from the output lines; and a
traction battery coupled across the output lines, said traction
battery to provide an additional source of current, upon demand, to
the electric motor.
2. The system of claim 1 wherein the turbogenerator comprises: a
shaft; a generator, coupled to the shaft, to generate the AC power;
a compressor, coupled to the shaft, to provide a supply of
compressed air; a combustor coupled to receive the supply of
compressed air and the fuel, said combustor to combust the fuel and
to provide exhaust gas; a turbine coupled the shaft and coupled to
receive the exhaust gas, said exhaust gas to flow through the
turbine to control a rotational speed of the shaft; and a
recuperator including a high pressure side coupled between the
compressor and the combustor, and a low pressure side coupled to
receive the exhaust gas from the turbine.
3. The system of claim 1 further comprising a DC/DC converter to
convert the DC voltage on the DC bus to a regulated low DC voltage,
under control of the power controller.
4. The system of claim 1 further comprising a break resistor
controllably coupled to the DC bus, the break resistor to sink DC
power from the DC bus under control of the power controller.
5. The system of claim 1 further comprising one or more additional
motors controllably coupled to the output lines.
6. The system of claim 1 further comprising: a second electric
motor; a second drive control unit coupled between the output lines
and the second electric motor, said second drive control unit,
under control of the power controller, to couple or isolate the
second electric motor to or from the output lines; and a second
traction battery coupled across the output lines, said traction
battery to provide a second additional source of current, upon
demand, to the second electric motor.
7. The system of claim 1 wherein the turbogenerator is a
motor/generator and said first and second power converters are
bi-directional, said power controller, in a startup mode, to
configure (i) the drive control unit to isolate the electric motor
from the output lines, (ii) the second power converter to supply a
startup DC voltage, generated by the traction battery, on the
output lines to the DC bus, and (iii) the first power converter to
convert the startup DC voltage on the DC bus to power the
motor/generator.
8. The system of claim 1 wherein the traction battery comprises one
of the following: a lead-acid, nickel-cadmium, nickel-metal
hydride, sodium-sulphur, sodium-nickel chloride, zinc-bromine,
zinc-air, and lithium battery.
9. The system of claim 1 wherein the turbogenerator and the
traction battery, in combination, to provide DC power to the
electric motor.
10. The system of claim 1 wherein the electric motor is an AC
electric motor, and wherein the system further comprises a DC/AC
converter coupled between the drive control unit and the AC
electric motor.
11. The system of claim 1 wherein the power controller, in response
to a brake signal, configures the drive control unit to provide a
recharging DC power, generated by the electric motor, to the
traction battery.
12. The system of claim 11 wherein the power controller, in
response to the brake signal, further configures the first and
second power converters to supply the operating DC power on the
output lines to charge the traction battery.
13. The system of claim 1 further comprising an additional
turbogenerator coupled to the fuel source and to generate
additional AC power, said power controller to independently
regulate the fuel to said turbogenerator and said additional
turbogenerator, independent of the DC voltage on the DC bus.
14. The system of claim 2 further comprising a temperature sensor
coupled to the turbine to sense a temperature, said sensor coupled
to the power controller, said power controller to vary the fuel to
the combustor to regulate the temperature, said temperature being
independent of the DC voltage on the DC bus.
15. A hybrid electric vehicle, comprising: one or more input
devices to provide one or more user inputs; a fuel source; a
turbogenerator to generate AC power; a power controller
electrically coupled to the turbogenerator and coupled to receive
the user inputs, said power controller including first and second
power converters, said first power converter to convert said AC
power to a DC voltage on a DC bus, and said second power converter
to convert said DC voltage on said DC bus to an operating DC
voltage on output lines, said power controller to regulate the fuel
flow to the turbogenerator based on at least one user input,
independent of the DC voltage on the DC bus; an electric motor; a
drive control unit coupled between the output lines and the
electric motor, said drive control unit, under control of the power
controller, to couple or isolate the electric motor to or from the
output lines; and a traction battery coupled across the output
lines, said traction battery to provide an additional source of
current to the electric motor.
16. The vehicle of claim 15 wherein the turbogenerator comprises: a
shaft; a generator, coupled to the shaft, to generate the AC power;
a compressor, coupled to the shaft, to provide a supply of
compressed air; a combustor coupled to receive the supply of
compressed air and the fuel, said combustor to combust the fuel and
to provide exhaust gas; a turbine coupled the shaft and coupled to
receive the exhaust gas, said exhaust gas to flow through the
turbine to control a rotational speed of the shaft; and a
recuperator including a high pressure side coupled between the
compressor and the combustor, and a low pressure side coupled to
receive the exhaust gas from the turbine.
17. The vehicle of claim 15 further comprising a DC/DC converter to
convert the DC voltage on the DC bus to a regulated low DC voltage,
under control of the power controller.
18. The vehicle of claim 15 further comprising a break resistor
controllably coupled to the DC bus, the break resistor to sink
current from the DC bus under control of the power controller.
19. The vehicle of claim 15 further comprising one or more
additional motors controllably coupled to the output lines.
20. The vehicle of claim 15 further comprising: a second electric
motor; a second drive control unit coupled between the output lines
and the second electric motor, said second drive control unit,
under control of the power controller, to couple or isolate the
second electric motor to or from the output lines; and a second
traction battery coupled across the output lines, said traction
battery to provide a second additional source of current, upon
demand, to the second electric motor.
21. The vehicle of claim 15 further comprising an additional
turbogenerator coupled to the fuel source and to generate
additional AC power, said power controller to independently
regulate the fuel to said turbogenerator and said additional
turbogenerator, independent of the DC voltage on the DC bus.
22. The vehicle of claim 15 wherein the one or more user inputs
comprise START, POWER, BRAKE, and STOP signals.
23. The vehicle of claim 22 wherein the power controller, in
response to the START signal, configures (i) the drive control unit
to isolate the electric motor from the output lines, (ii) the
second power converter to supply a startup DC voltage, generated by
the traction battery, on the output lines to the DC bus, and (iii)
the first power converter to convert the startup DC voltage on the
DC bus to power the motor/generator.
24. The vehicle of claim 22 wherein the power controller, in
response to the POWER signal, to correspondingly adjust the fuel to
the turbogenerator to adjust an operating DC power on the output
lines.
25. The vehicle of claim 24 wherein, when the operating DC power
reaches a maximum power value, said traction battery provides
instantaneous current on the output lines to drive the electric
motor.
26. The vehicle of claim 22 wherein the power controller, in
response to the BRAKE signal, configures the drive control unit to
provide a recharging DC power, generated by the electric motor, to
the traction battery.
27. The vehicle of claim 26 wherein the power controller, in
response to the BRAKE signal, simultaneously configures the first
and second power converters to supply the operating DC power on the
output lines to charge the traction battery.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from co-pending U.S. patent
application Ser. No. 09/207,817, filed Dec. 8, 1998, assigned to
the assignee of the present application, and U.S. Provisional
Application Serial No. 60/248,090, filed on Nov. 13, 2000, the
contents of which are fully incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to power generation,
distribution and processing systems and in particular to a turbine
power unit for a hybrid vehicle application.
[0004] 2. Background of the Invention
[0005] The most popular power source for automotive applications is
an internal combustion engine connected to a mechanical drive train
which, in turn, rotates at least one wheel to drive the automobile.
However, state and federal automotive emission laws are becoming
increasingly more difficult to meet using current internal
combustion engines powered by hydrocarbon fuels which emit large
quantities of carbon dioxide, carbon monoxide, and various nitrogen
oxides as by-products. Additionally, even the most efficient
internal combustion engines are not very efficient, having a
maximum efficiency of approximately 35% or less. The efficiency of
an internal combustion engine increases as the energy output
increases. During urban driving cycles, where the required power
output is the lowest, the efficiency is even lower.
[0006] As an alternative, electric vehicles were developed with the
electric energy stored in large battery packs that replace the
internal combustion engine and powered the automobile. The stored
energy drives at least one electric motor which in turn rotates at
least one drive wheel. Electric vehicles meet many of the criteria
for clean emissions required by state and federal legislation.
However, general acceptance of electric vehicles as a viable
transportation option has been limited by travel range, maintenance
and life constraints.
[0007] Similarly, hybrid buses using reciprocating internal
combustion engines suffer from other drawbacks, such as noise,
vibration, oil leakage, coolant leakage, exhaust emissions, and
smell.
SUMMARY OF THE INVENTION
[0008] A power generation system for a hybrid electric vehicle
includes a fuel source, a turbogenerator coupled to the fuel
source, and a power controller. The power controller is
electrically coupled to the turbogenerator, and includes first and
second power converters. The first power converter converts AC
power from the turbogenerator to DC power on a DC bus, and the
second power converter converts the DC power on the DC bus to an
operating DC power on output lines. The power controller regulates
the fuel to the turbogenerator, independent of DC voltage on the DC
bus. The system further includes an electric motor, a drive control
unit, and a traction battery. The drive control unit is coupled
between the output lines and the electric motor to couple or
isolate the electric motor to or from the output lines, in response
to the power controller. The traction battery is coupled across the
output lines, and provides an additional source of current, upon
demand, to the electric motor.
[0009] Other embodiments are disclosed and claimed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1A is perspective view, partially in section, of an
integrated turbogenerator system.
[0011] FIG. 1B is a magnified perspective view, partially in
section, of the motor/generator portion of the integrated
turbogenerator of FIG. 1A.
[0012] FIG. 1C is an end view, from the motor/generator end, of the
integrated turbogenerator of FIG. 1A.
[0013] FIG. 1D is a magnified perspective view, partially in
section, of the combustor-turbine exhaust portion of the integrated
turbogenerator of FIG. 1A.
[0014] FIG. 1E is a magnified perspective view, partially in
section, of the compressor-turbine portion of the integrated
turbogenerator of FIG. 1A.
[0015] FIG. 2 is a block diagram schematic of a turbogenerator
system including a power controller having decoupled rotor speed,
operating temperature, and DC bus voltage control loops.
[0016] FIG. 3 is a block diagram of power controller 310 used in a
power generation and distribution system according to one
embodiment.
[0017] FIG. 4 is a detailed block diagram of bi-directional power
converter 314 in the power controller 310 illustrated in FIG.
3.
[0018] FIG. 5 is a simplified block diagram of turbogenerator
system 200 including the power architecture of the power controller
illustrated in FIG. 3.
[0019] FIG. 6 is a block diagram a typical implementation of the
power generation and distribution system, including power
controller illustrated in FIGS. 3-6.
[0020] FIG. 7 is a schematic diagram of the internal power
architecture of the power controller illustrated in FIGS. 3-7.
[0021] FIG. 8 is a functional block diagram of a power controller
interface between a vehicle drive system and a turbogenerator
illustrated in FIGS. 3-8.
[0022] FIG. 9 is a functional block diagram of a power controller
interface between a vehicle drive system and a turbogenerator as
shown in FIG. 8 including a DC/DC converter.
[0023] FIG. 10 is a schematic diagram of a power controller
interface between a vehicle drive system and a turbogenerator as
shown in FIGS. 3-10, according to one embodiment.
[0024] FIG. 11 is a block diagram of the logic architecture for the
power controller including external interfaces, as shown in FIGS.
3-11.
[0025] FIG. 12 is a block diagram of an EGT control mode loop for
regulating the temperature of turbogenerator 358 by operation of
fuel control system 342.
[0026] FIG. 13 is a block diagram of a speed control mode loop for
regulating the rotating speed of turbogenerator 358 by operation of
fuel control system 342.
[0027] FIG. 14 is a block diagram of a power control mode loop for
regulating the power producing potential of turbogenerator 358.
[0028] FIG. 15 is a state diagram showing various operating states
of power controller 310.
[0029] FIG. 16 is a block diagram of power controller 310
interfacing with a turbogenerator 358 and fuel control system
342.
[0030] FIG. 17 is a block diagram of the power controllers in
multi-pack configuration.
[0031] FIG. 18 is a diagram of power controller 310, including
brake resistor 912 and brake resistor modulation switch 914.
[0032] FIG. 19 is a diagram of a hybrid electric vehicle, according
to one embodiment.
[0033] FIG. 20 is a block diagram showing the interplay between a
vehicle drive system and power controller 310, according to one
embodiment.
DETAILED DESCRIPTION
[0034] Mechanical Structural Embodiment of a Turbogenerator
[0035] With reference to FIG. 1A, an integrated turbogenerator 1
according to the present disclosure generally includes
motor/generator section 10 and compressor-turbine section 30.
Compressor-turbine section 30 includes exterior can 32, compressor
40, combustor 50 and turbine 70. A recuperator 90 may be optionally
included.
[0036] Referring now to FIG. 1B and FIG. 1C, in a currently
preferred embodiment of the present disclosure, motor/generator
section 10 may be a permanent magnet motor generator having a
permanent magnet rotor or sleeve 12. Any other suitable type of
motor generator may also be used. Permanent magnet rotor or sleeve
12 may contain a permanent magnet 12M. Permanent magnet rotor or
sleeve 12 and the permanent magnet disposed therein are rotatably
supported within permanent magnet motor/generator stator 14.
Preferably, one or more compliant foil, fluid film, radial, or
journal bearings 15A and 15B rotatably support permanent magnet
rotor or sleeve 12 and the permanent magnet disposed therein. All
bearings, thrust, radial or journal bearings, in turbogenerator 1
may be fluid film bearings or compliant foil bearings.
Motor/generator housing 16 encloses stator heat exchanger 17 having
a plurality of radially extending stator cooling fins 18. Stator
cooling fins 18 connect to or form part of stator 14 and extend
into annular space 10A between motor/generator housing 16 and
stator 14. Wire windings 14W exist on permanent magnet
motor/generator stator 14.
[0037] Referring now to FIG. 1D, combustor 50 may include
cylindrical inner wall 52 and cylindrical outer wall 54.
Cylindrical outer wall 54 may also include air inlets 55.
Cylindrical walls 52 and 54 define an annular interior space 50S in
combustor 50 defining an axis 50A. Combustor 50 includes a
generally annular wall 56 further defining one axial end of the
annular interior space of combustor 50. Associated with combustor
50 may be one or more fuel injector inlets 58 to accommodate fuel
injectors which receive fuel from fuel control element 50P as shown
in FIG. 2, and inject fuel or a fuel air mixture to interior of 50S
combustor 50. Inner cylindrical surface 53 is interior to
cylindrical inner wall 52 and forms exhaust duct 59 for turbine
70.
[0038] Turbine 70 may include turbine wheel 72. An end of combustor
50 opposite annular wall 56 further defines an aperture 71 in
turbine 70 exposed to turbine wheel 72. Bearing rotor 74 may
include a radially extending thrust bearing portion, bearing rotor
thrust disk 78, constrained by bilateral thrust bearings 78A and
78B. Bearing rotor 74 may be rotatably supported by one or more
journal bearings 75 within center bearing housing 79. Bearing rotor
thrust disk 78 at the compressor end of bearing rotor 74 is
rotatably supported preferably by a bilateral thrust bearing 78A
and 78B. Journal or radial bearing 75 and thrust bearings 78A and
78B may be fluid film or foil bearings.
[0039] Turbine wheel 72, bearing rotor 74 and compressor impeller
42 may be mechanically constrained by tie bolt 74B, or other
suitable technique, to rotate when turbine wheel 72 rotates.
Mechanical link 76 mechanically constrains compressor impeller 42
to permanent magnet rotor or sleeve 12 and the permanent magnet
disposed therein causing permanent magnet rotor or sleeve 12 and
the permanent magnet disposed therein to rotate when compressor
impeller 42 rotates.
[0040] Referring now to FIG. 1E, compressor 40 may include
compressor impeller 42 and compressor impeller housing 44.
Recuperator 90 may have an annular shape defined by cylindrical
recuperator inner wall 92 and cylindrical recuperator outer wall
94. Recuperator 90 contains internal passages for gas flow, one set
of passages, passages 33 connecting from compressor 40 to combustor
50, and one set of passages, passages 97, connecting from turbine
exhaust 80 to turbogenerator exhaust output 2.
[0041] Referring again to FIG. 1B and FIG. 1C, in operation, air
flows into primary inlet 20 and divides into compressor air 22 and
motor/generator cooling air 24. Motor/generator cooling air 24
flows into annular space 10A between motor/generator housing 16 and
permanent magnet motor/generator stator 14 along flow path 24A.
Heat is exchanged from stator cooling fins 18 to generator cooling
air 24 in flow path 24A, thereby cooling stator cooling fins 18 and
stator 14 and forming heated air 24B. Warm stator cooling air 24B
exits stator heat exchanger 17 into stator cavity 25 where it
further divides into stator return cooling air 27 and rotor cooling
air 28. Rotor cooling air 28 passes around stator end 13A and
travels along rotor or sleeve 12. Stator return cooling air 27
enters one or more cooling ducts 14D and is conducted through
stator 14 to provide further cooling. Stator return cooling air 27
and rotor cooling air 28 rejoin in stator cavity 29 and are drawn
out of the motor/generator 10 by exhaust fan 11 which is connected
to rotor or sleeve 12 and rotates with rotor or sleeve 12. Exhaust
air 27B is conducted away from primary air inlet 20 by duct
10D.
[0042] Referring again to FIG. 1E, compressor 40 receives
compressor air 22. Compressor impeller 42 compresses compressor air
22 and forces compressed gas 22C to flow into a set of passages 33
in recuperator 90 connecting compressor 40 to combustor 50. In
passages 33 in recuperator 90, heat is exchanged from walls 98 of
recuperator 90 to compressed gas 22C. As shown in FIG. 1E, heated
compressed gas 22H flows out of recuperator 90 to space 35 between
cylindrical inner surface 82 of turbine exhaust 80 and cylindrical
outer wall 54 of combustor 50. Heated compressed gas 22H may flow
into combustor 54 through sidewall ports 55 or main inlet 57. Fuel
(not shown) may be reacted in combustor 50, converting chemically
stored energy to heat. Hot compressed gas 51 in combustor 50 flows
through turbine 70 forcing turbine wheel 72 to rotate. Movement of
surfaces of turbine wheel 72 away from gas molecules partially
cools and decompresses gas 51D moving through turbine 70. Turbine
70 is designed so that exhaust gas 107 flowing from combustor 50
through turbine 70 enters cylindrical passage 59. Partially cooled
and decompressed gas in cylindrical passage 59 flows axially in a
direction away from permanent magnet motor/generator section 10,
and then radially outward, and then axially in a direction toward
permanent magnet motor/generator section 10 to passages 97 of
recuperator 90, as indicated by gas flow arrows 108 and 109
respectively.
[0043] In an alternate embodiment of the present disclosure, low
pressure catalytic reactor 80A may be included between fuel
injector inlets 58 and recuperator 90. Low pressure catalytic
reactor 80A may include internal surfaces (not shown) having
catalytic material (e.g., Pd or Pt, not shown) disposed on them.
Low pressure catalytic reactor 80A may have a generally annular
shape defined by cylindrical inner surface 82 and cylindrical low
pressure outer surface 84. Unreacted and incompletely reacted
hydrocarbons in gas in low pressure catalytic reactor 80A react to
convert chemically stored energy into additional heat, and to lower
concentrations of partial reaction products, such as harmful
emissions including nitrous oxides (NOx).
[0044] Gas 110 flows through passages 97 in recuperator 90
connecting from turbine exhaust 80 or catalytic reactor 80A to
turbogenerator exhaust output 2, as indicated by gas flow arrow
112, and then exhausts from turbogenerator 1, as indicated by gas
flow arrow 113. Gas flowing through passages 97 in recuperator 90
connecting from turbine exhaust 80 to outside of turbogenerator 1
exchanges heat to walls 98 of recuperator 90. Walls 98 of
recuperator 90 heated by gas flowing from turbine exhaust 80
exchange heat to gas 22C flowing in recuperator 90 from compressor
40 to combustor 50.
[0045] Turbogenerator 1 may also include various electrical sensor
and control lines for providing feedback to power controller 201
and for receiving and implementing control signals as shown in FIG.
2.
[0046] Alternative Mechanical Structural Embodiments of the
Integrated Turbo generator
[0047] The integrated turbogenerator disclosed above is exemplary.
Several alternative structural embodiments are disclosed
herein.
[0048] In one alternative embodiment, air 22 may be replaced by a
gaseous fuel mixture. In this embodiment, fuel injectors may not be
necessary. This embodiment may include an air and fuel mixer
upstream of compressor 40.
[0049] In another alternative embodiment, fuel may be conducted
directly to compressor 40, for example by a fuel conduit connecting
to compressor impeller housing 44. Fuel and air may be mixed by
action of the compressor impeller 42. In this embodiment, fuel
injectors may not be necessary.
[0050] In another alternative embodiment, combustor 50 may be a
catalytic combustor.
[0051] In still another alternative embodiment, geometric
relationships and structures of components may differ from those
shown in FIG. 1A. Permanent magnet motor/generator section 10 and
compressor/combustor section 30 may have low pressure catalytic
reactor 80A outside of annular recuperator 90, and may have
recuperator 90 outside of low pressure catalytic reactor 80A. Low
pressure catalytic reactor 80A may be disposed at least partially
in cylindrical passage 59, or in a passage of any shape confined by
an inner wall of combustor 50. Combustor 50 and low pressure
catalytic reactor 80A may be substantially or completely enclosed
with an interior space formed by a generally annularly shaped
recuperator 90, or a recuperator 90 shaped to substantially enclose
both combustor 50 and low pressure catalytic reactor 80A on all but
one face.
[0052] An integrated turbogenerator is a turbogenerator in which
the turbine, compressor, and generator are all constrained to
rotate based upon rotation of the shaft to which the turbine is
connected. The methods and apparatus disclosed herein are may be
used in connection with a turbogenerator, and may be used in
connection with an integrated turbogenerator.
[0053] Control System
[0054] Referring now to FIG. 2, one embodiment is shown in which a
turbogenerator system 200 includes power controller 201 which has
three substantially decoupled control loops for controlling (1)
rotary speed, (2) temperature, and (3) DC bus voltage. A more
detailed description of an appropriate power controller is
disclosed in U.S. patent application Ser. No. 09/207,817, filed
Dec. 8, 1998 in the names of Gilbreth, Wacknov and Wall, and
assigned to the assignee of the present application which is
incorporated herein in its entirety by this reference.
[0055] Referring still to FIG. 2, turbogenerator system 200
includes integrated turbogenerator 1 and power controller 201.
Power controller 201 includes three decoupled or independent
control loops.
[0056] A first control loop, temperature control loop 228,
regulates a temperature related to the desired operating
temperature of primary combustor 50 to a set point, by varying fuel
flow from fuel control element 50P to primary combustor 50.
Temperature controller 228C receives a temperature set point, T*,
from temperature set point source 232, and receives a measured
temperature from temperature sensor 226S connected to measured
temperature line 226. Temperature controller 228C generates and
transmits over fuel control signal line 230 to fuel pump 50P a fuel
control signal for controlling the amount of fuel supplied by fuel
pump 50P to primary combustor 50 to an amount intended to result in
a desired operating temperature in primary combustor 50.
Temperature sensor 226S may directly measure the temperature in
primary combustor 50 or may measure a temperature of an element or
area from which the temperature in the primary combustor 50 may be
inferred.
[0057] A second control loop, speed control loop 216, controls
speed of the shaft common to the turbine 70, compressor 40, and
motor/generator 10, hereafter referred to as the common shaft, by
varying torque applied by the motor generator to the common shaft.
Torque applied by the motor generator to the common shaft depends
upon power or current drawn from or pumped into windings of
motor/generator 10. Bi-directional generator power converter 202 is
controlled by rotor speed controller 216C to transmit power or
current in or out of motor/generator 10, as indicated by
bi-directional arrow 242. A sensor in turbogenerator 1 senses the
rotary speed on the common shaft and transmits that rotary speed
signal over measured speed line 220. Rotor speed controller 216
receives the rotary speed signal from measured speed line 220 and a
rotary speed set point signal from a rotary speed set point source
218. Rotary speed controller 216C generates and transmits to
generator power converter 202 a power conversion control signal on
line 222 controlling generator power converter 202's transfer of
power or current between AC lines 203 (i.e., from motor/generator
10) and DC bus 204. Rotary speed set point source 218 may convert
to the rotary speed set point a power set point P* received from
power set point source 224.
[0058] A third control loop, voltage control loop 234, controls bus
voltage on DC bus 204 to a set point by transferring power or
voltage between DC bus 204 and any of (1) vehicle drive system 208
and/or (2) electrical output 210, and/or (3) by transferring power
or voltage from DC bus 204 to dynamic brake resistor 214. A sensor
measures voltage DC bus 204 and transmits a measured voltage signal
over measured voltage line 236. Bus voltage controller 234C
receives the measured voltage signal from voltage line 236 and a
voltage set point signal V* from voltage set point source 238. Bus
voltage controller 234C generates and transmits signals to
bi-directional load power converter 206 and power converter 212
controlling their transmission of power or voltage between DC bus
204, vehicle drive system 208, and electrical output 210,
respectively. In addition, bus voltage controller 234 transmits a
control signal to control connection of dynamic brake resistor 214
to DC bus 204.
[0059] Power controller 201 regulates temperature to a set point by
varying fuel flow, adds or removes power or current to
motor/generator 10 under control of generator power converter 202
to control rotor speed to a set point as indicated by
bi-directional arrow 242, and controls bus voltage to a set point
by (1) applying or removing power from DC bus 204 under the control
of power converter 206 as indicated by bi-directional arrow 244,
(2) applying power to the electrical output 210 under the control
of power converter 212, and (3) by removing power from DC bus 204
by modulating the connection of dynamic brake resistor 214 to DC
bus 204.
[0060] Referring to FIG. 3, power controller 310, which is an
embodiment of power controller 201, includes bi-directional,
reconfigurable, power converters 314 and 316 and power converter
322 used with common DC bus 324. Power converters 314 and 316
operate essentially as a customized, bi-directional switching
converters configured, under the control of power controller 310,
to provide an interface for a specific energy component 312 or 318
to DC bus 324. Power converter 322 also operates under the control
of power controller 310, to supply power to electrical output 320.
Power controller 310 controls the way in which each energy
component 312, 318 or 320, at any moment, will sink or source
power, as the case may be, and the manner in which DC bus 324 is
regulated. In this way, various energy components can be used to
supply, store and/or use power in an efficient manner.
[0061] Energy source 312 may be a turbogenerator system,
photovoltaics, wind turbine or any other conventional or newly
developed source. Electrical output 320 may provide DC power (e.g.,
12 volts) to the electrical systems of the vehicle, including such
systems as a radio, power windows, driver display or any other
electrical system of a vehicle. Vehicle drive system 318 includes a
traction battery, drive control unit and electric motor, as shown
in FIG. 21.
[0062] Referring now also to FIG. 4, a detailed block diagram of
bi-directional power converter 314 shown in FIG. 3, is illustrated.
Energy source 312 is connected to DC bus 324 via power converter
314. Energy source 312 may be, for example, a turbogenerator
including a turbine engine driving a motor/generator to produce AC
which is applied to power converter 314. DC bus 324 connects power
converter 314 to vehicle drive system 318. Power converter 314
includes input filter 326, power switching system 328, output
filter 334, signal processor (SP) 330 and main CPU 332. In
operation, energy source 312 applies AC to input filter 326 in
power converter 314. The filtered AC is then applied to power
switching system 328 which may conveniently include a series of
insulated gate bipolar transistor (IGBT) switches operating under
the control of SP 330 which is controlled by main CPU 332. Other
conventional or newly developed switches may be utilized as well.
The output of the power switching system 328 is applied to output
filter 334 which then applies the filtered DC to DC bus 324.
[0063] Power converters 314 and 316 operate essentially as
customized, bi-directional switching converters under the control
of main CPU 332, which uses SP 330 to perform its operations. Main
CPU 332 provides both local control and sufficient intelligence to
form a distributed processing system. Power converters 314 and 316
are tailored to provide an interface for a specific energy
component to DC bus 324, while power converter 322 is tailored to
provide power to the vehicle electrical systems via electrical
output 320 from DC bus 324.
[0064] Main CPU 332 controls the way in which each energy component
312, 318 and 320 sinks or sources power, as the case may be, and
the way in which DC bus 324 is regulated at any time. In
particular, main CPU 332 reconfigures the power converters 314, 316
and 322 into different configurations for different modes of
operation. In this way, various energy components 312, 318 and 320
can be used to supply, store and/or use power in an efficient
manner.
[0065] In the case of a turbogenerator, for example, power
controller 310 may regulate bus voltage independently of
turbogenerator speed.
[0066] FIG. 3 shows a system topography in which DC bus 324, which
may be regulated at 800 VDC, for example, is at the center of a
star pattern network. In general, energy source 312 provides power
to DC bus 324 via bi-directional power converter 314 during normal
power generation mode. Similarly, during normal power generation
mode, power converter 316 converts the power on DC bus 324 to the
form required by vehicle drive system 318. During other modes of
operation, such as battery start up, power converters 314 and 316
may be controlled by the main processor to operate in different
manners.
[0067] For example, energy may be needed during battery start up to
start a prime mover, such as a turbine engine in a turbogenerator
included in energy source 312. This energy may come from a battery
source in vehicle drive system 318, and in particular from traction
battery 1050, as shown in FIG. 21.
[0068] During battery start up, power converter 316 applies power
from the traction battery 1050 to DC bus 324. Power converter 314
applies power required from DC bus 324 to energy source 312 for
startup. During battery start up, a turbine engine of a
turbogenerator in energy source 312 may be controlled in a local
feedback loop to maintain the turbine engine speed, typically in
revolutions per minute (RPM).
[0069] Referring to FIG. 5, a simplified block diagram of
turbogenerator system 200 is illustrated. Turbogenerator system 200
includes a fuel metering system 342, turbogenerator 358, power
controller 310, electrical system conversion process 362,
electrical output 364 and vehicle drive system 360. The fuel
metering system 342 is matched to the available fuel and pressure.
The power controller 310 converts the electricity from
turbogenerator 358 into regulated DC applied to DC bus 324 and then
converts the DC power on DC bus 324 to operating DC power to supply
the vehicle drive system 360.
[0070] By separating the engine control from the power conversion
processes, greater control of both processes is realized. All of
the interconnections are provided by communications bus and power
connection 352.
[0071] The power controller 310 includes bi-directional engine
power conversion process 354 and bi-directional vehicle drive
system power conversion process 356 between turbogenerator 358 and
the vehicle drive system 360. The bi-directional (i.e.
reconfigurable) power conversion processes 354 and 356 are used
with common regulated DC bus 324 for connection with turbogenerator
358 and vehicle drive system 360. Each power conversion process 354
and 356 operates essentially as a customized bi-directional
switching conversion process configured, under the control of the
power controller 310, to provide an interface for a specific energy
component, such as turbogenerator 358 or vehicle drive system 360,
to DC bus 324. The power controller 310 controls the way in which
each energy component, at any moment, will sink or source power,
and the manner in which DC bus 324 is regulated. Both of these
power conversion processes 354 and 356 are capable of operating in
a forward or reverse direction. This allows starting turbogenerator
358 from the traction battery 1050 located within the vehicle drive
system 360. The embodiments disclosed herein permit the use of
virtually any technology that can convert its energy to/from
electricity,
[0072] The electrical output 364 and its electrical system
conversion process 362 need not be contained inside the power
controller 310.
[0073] Referring to FIG. 6, a typical implementation of power
controller 310 with a turbogenerator 358, including turbine engine
448 and motor/generator 10, is shown. The power controller 310
includes motor/generator converter 372 and output converter 374
between turbogenerator 358 and the vehicle drive system 360.
[0074] In particular, in the normal power generation mode, the
motor/generator converter 372 provides for AC to DC power
conversion between motor/generator 10 and DC bus 324 and the output
converter 374 provides for DC to operating DC power conversion
between DC bus 324 and vehicle drive system 360. Both of these
power converters 372 and 374 are capable of operating in a forward
or reverse direction. This allows starting turbogenerator 358 by
supplying power to motor/generator 10 from the traction battery
1050, located within vehicle drive system 360, as shown in FIG.
21.
[0075] Referring now also to FIG. 7, a partial schematic of a
typical internal power architecture of a system as shown in FIG. 6,
is shown in greater detail. Turbogenerator 358 includes an integral
motor/generator 10, such as a permanent magnet motor/generator,
rotationally coupled to the turbine engine 448 therein that can be
used as either a motor (for starting) or a generator (for normal
mode of operation). Because all of the controls can be performed in
the digital domain and all switching (except for one output
contactor such as output contactor 510 shown below in FIG. 10) is
done with solid state switches, it is easy to shift the direction
of the power flow as needed. This permits very tight control of the
speed of turbine engine 448 during starting and stopping.
[0076] Power controller 310 includes motor/generator converter 372
and output converter 374. Motor/generator converter 372 includes
IGBT switches, such as a seven-pack IGBT module driven by control
logic 398, providing a variable voltage, variable frequency 3-phase
drive to the motor/generator 10 from DC bus 324 during startup.
Inductors 402 are utilized to minimize any current surges
associated with the high frequency switching components which may
affect the motor/generator 10 to increase operating efficiency.
[0077] Motor/Generator converter 372 controls motor/generator 10
and the turbine engine 448 of turbogenerator 358. Motor/generator
converter 372 incorporates gate driver and fault sensing circuitry
as well as a seventh IGBT used as a switch such as switch 614 to
dump power into a resistor, such as brake resistor 612, as shown in
FIG. 19 below. The gate drive inputs and fault outputs require
external isolation. Four external, isolated power supplies are
required to power the internal gate drivers. Motor/generator
converter 372 is typically used in a turbogenerator system that
generates DC voltage at its output terminals delivering power to
the vehicle drive system 360. During startup the direction of power
flow through motor/generator converter 372 reverses. When the
turbine engine of turbogenerator 358 is being started, power is
supplied to the DC bus 324 from the traction battery 1050 located
within the vehicle drive system 360, as shown in FIG. 21. The DC on
DC bus 324 is then converted to variable voltage, variable
frequency AC voltage to operate motor/generator 10 as a motor to
start the turbine engine 448 in turbogenerator 358.
[0078] For start up operation, control logic 410 drives output
controller 374 to boost the voltage from the traction battery 1050
to provide start power to the motor/generator converter 372. After
turbogenerator 358 is running, output converter 374 is used to
convert the regulated DC bus voltage on DC bus 324 to the operating
DC voltage to drive the vehicle drive system 360.
[0079] DC/DC converter 362, driven by control logic 416, may also
be used to provide power from the DC bus 324 to the other
electrical systems.
[0080] The energy needed to start turbogenerator 58 may come from a
battery source within vehicle drive system 360. Enough power is
created to run the fuel metering circuit 342, start the engine, and
close the various solenoids (including the dump valve on the
engine). After turbine engine 448 becomes self-sustaining, the
traction battery 1050 starts to replace the energy used to start
turbine engine 448, by drawing power from DC bus 324.
[0081] Power controller 310 senses the presence of other
controllers during the initial power up phase. If another
controller is detected, the controller must be part of a
multi-pack, and proceeds to automatically configure itself for
operation as part of a multi-pack.
[0082] Referring now to FIG. 8, a functional block diagram of an
interface between vehicle drive system 360 and turbogenerator 358,
using power controller 310, is shown. In this example, power
controller 310 includes filter 434, two bi-directional converters
372 and 374, connected by DC bus 324 and filter 444.
Motor/generator converter 372 starts turbine engine 448, using
motor/generator 10 as a motor, from battery power. Output converter
374 produces DC power using an output from motor/generator
converter 372 to draw power from high-speed motor/generator 10.
Power controller 310 also regulates fuel to turbine engine 448 via
fuel control 342 and provides communications between units (in
paralleled systems) and to external entities.
[0083] During a battery startup sequence, a traction battery 1050
within vehicle drive system 360 supplies starting power to turbine
448 by output converter 374 to apply DC to DC bus 324, and then
converting the DC to variable voltage, variable frequency 3-phase
power in motor/generator converter 372, according to one
embodiment.
[0084] As is illustrated in FIG. 9, where there are other
electrical systems to be powered during or prior to startup, the
start sequence under the control of power controller 310 is the
same as the battery start sequence shown in FIG. 8, with the
exception that power can also be applied to electrical output 470
via DC converter 362 attached to DC bus 324.
[0085] Referring to FIG. 10, a more detailed schematic illustration
of an interface between vehicle drive system 360 and turbogenerator
358 using power controller 310 is illustrated. Control logic 484
provides power to fuel cutoff solenoids 498, fuel control system
342 and igniter 502. DC converter 362 and electrical output 470, if
used, connect directly to DC bus 324. Fuel control system 342 may
include a fuel control valve or fuel compressor 370 operated from a
separate variable speed drive which can also derive its power
directly from DC bus 324.
[0086] Solid state (IGBT) switches 512 associated with
motor/generator converter 372 are also driven from control logic
484, providing a variable voltage, variable frequency 3-phase drive
to motor/generator 10 to start turbine engine 448. Control logic
484 receives feedback via current sensors Isens from
motor/generator filter 488 as turbine engine 448 is ramped up in
speed to complete the start sequence. When turbine engine achieves
a self-sustaining speed of, for example, approx. 40,000 RPM,
motor/generator converter 372 changes its mode of operation to
boost the motor/generator output voltage and provide a regulated DC
bus voltage.
[0087] The voltage, Vsens, between output contactor 510 and vehicle
drive system 360 is applied as an input to control logic 484. The
temperature of turbine engine 448, Temp Sens, is also applied as an
input to control logic 484. Control logic 484 drives IGBT gate
drivers 482, relay or contactor drivers 501, release valve 504,
fuel cutoff solenoid 498, and fuel supply system 342.
[0088] Motor/generator filter 488 associated with motor/generator
converter 372 includes three inductors to remove the high frequency
switching component from motor/generator 10 to increase operating
efficiency. Output contactor 510 disengages output converter 374 in
the event of a unit fault.
[0089] During a start sequence, control logic 484 opens fuel cutoff
solenoid 498 and maintains it open until the system is commanded
off. Fuel control system 342 may be a variable flow valve providing
a dynamic regulating range, allowing minimum fuel during start and
maximum fuel at full load. A variety of fuel controllers, including
but not limited to, liquid and gas fuel controllers, may be
utilized. Fuel control can be implemented by various
configurations, including but not limited to single or dual stage
gas compressor such as fuel control valve 370 accepting fuel
pressures as low as approximately 1 psig. Igniter 502, a spark type
device similar to a spark plug for an internal combustion engine,
is operated only during the start sequence.
[0090] DC/DC power converter 362, which connects directly to the DC
bus 324, may supply power to electrical output 470. Electrical
output 470 may be connected to any number of electrical systems
within a vehicle.
[0091] Referring to FIG. 11, power controller logic 530 includes
main CPU 332, motor/generator SP 534 and output SP 536. Main CPU
software program sequences events which occur inside power
controller logic 530 and arbitrates communications to externally
connected devices. Main CPU 332 is preferably a MC68332
microprocessor, available from Motorola Semiconductor, Inc. of
Phoenix, Ariz. Other suitable commercially available
microprocessors may be used as well. The software performs the
algorithms that control engine operation, determine power output
and detect system faults.
[0092] Commanded operating modes are used to determine how power is
switched through the major power converters in power controller
310. The software is responsible for turbine engine control and
issuing commands to other SP processors enabling them to perform
the motor/generator power converter and output/load power converter
power switching.
[0093] Motor/generator SP 534 and output SP 536 are connected to
main CPU 332 via serial peripheral interface (SPI) bus 538 to
perform motor/generator and output power converter control
functions. Motor/generator SP 534 is responsible for any switching
which occurs between DC bus 324 and motor/generator 10. Output SP
536 is responsible for any switching which occurs between DC bus
324 and vehicle drive system 360.
[0094] As illustrated in FIG. 7, motor/generator SP 534 operates
the IGBT module in motor/generator converter 372 via control logic
398 while output SP 536 operates DC output converter 374 via
control logic 410.
[0095] Local devices, such as a smart display 542, smart battery
544 and smart fuel control 546, are connected to main CPU 332 in
via intracontroller bus 540, which may be a RS485 communications
link. Smart display 542, smart battery 544 and smart fuel control
546 performs dedicated controller functions, including but not
limited to display, energy storage management, and fuel control
functions.
[0096] Main CPU 332 in power controller logic 530 is coupled to
user port 548 for connection to a computer, workstation, modem or
other data terminal equipment which allows for data acquisition
and/or remote control. User port 548 may be implemented using a
RS232 interface or other compatible interface.
[0097] Main CPU 332 in power controller logic 530 is also coupled
to maintenance port 550 for connection to a computer, workstation,
modem or other data terminal equipment which allows for remote
development, troubleshooting and field upgrades. Maintenance port
550 may be implemented using a RS232 interface or other compatible
interface.
[0098] The main CPU processor software communicates data through a
TCP/IP stack over intercontroller bus 552, typically an Ethernet 10
Base 2 interface, to gather data and send commands between power
controllers (as shown and discussed in detail with respect to FIG.
17). The main CPU processor software provides seamless operation of
multiple paralleled units as a single larger generator system. One
unit, the master, arbitrates the bus and sends commands to all
units.
[0099] Intercontroller bus 552, which may be a RS485 communications
link, provides high-speed synchronization of power output signals
directly between output converter SPs, such as output SP 536.
Although the main CPU software is not responsible for communicating
on the intercontroller bus 552, it informs output converter SPs,
including output SP 536, when main CPU 332 is selected as the
master. External option port bus 556, which may be a RS485
communications link, allows external devices, including but not
limited to power meter equipment and auto disconnect switches, to
be connected to motor/generator SP 534.
[0100] In operation, main CPU 332 begins execution with a power on
self-test when power is applied to the control board. External
devices are detected providing information to determine operating
modes the system is configured to handle. Power controller logic
530 waits for a start command by making queries to external
devices. Once received, power controller logic 530 sequences up to
begin producing power. As a minimum, main CPU 332 sends commands to
external smart devices 542, 544 and 546 to assist with bringing
power controller logic 530 online.
[0101] If selected as the master, the software may also send
commands to initiate the sequencing of other power controllers
(FIG. 17) connected in parallel. A stop command will shutdown the
system bringing it offline.
[0102] The main CPU 332 software interfaces with several electronic
circuits (not shown) on the control board to operate devices that
are universal to all power controllers 310. Interface to system I/O
begins with initialization of registers within power controller
logic 530 to configure internal modes and select external pin
control. Once initialized, the software has access to various
circuits including discrete inputs/outputs, analog inputs/outputs,
and communication ports. These external devices may also have
registers within them that require initialization before the device
is operational.
[0103] Continuing to refer to FIG. 11, main CPU 332 is responsible
for all communication systems in power controller logic 530. Data
transmission between a plurality of power controllers 310 is
accomplished through intercontroller bus 552. Main CPU 332
initializes the communications hardware attached to power
controller logic 530 for intercontroller bus 552.
[0104] Main CPU 332 provides control for external devices,
including smart devices 542, 544 and 546, which share information
to operate. Data transmission to external devices, including smart
display 542, smart battery 544 and smart fuel control 546 devices,
is accomplished through intracontroller communications bus 540.
Main CPU 332 initializes any communications hardware attached to
power controller logic 530 for intracontroller communications bus
540 and implements features defined for the bus master on
intracontroller communications bus 540.
[0105] Communications between devices such as switch gear and power
meters used for master control functions exchange data across
external equipment bus 556. Main CPU 332 initializes any
communications hardware attached to power controller logic 530 for
external equipment bus 556 and implements features defined for the
bus master on external equipment bus 556.
[0106] Communications with a user computer is accomplished through
user interface port 548. Main CPU 332 initializes any
communications hardware attached to power controller logic 530 for
user interface port 548. In one configuration, at power up, the
initial baud rate will be selected to 19200 baud, 8 data bits, 1
stop, and no parity. The user has the ability to adjust and save
the communications rate setting via user interface port 548 or
optional smart external display 542. The saved communications rate
is used the next time power controller logic 530 is powered on.
Main CPU 332 communicates with a modem (not shown), such as a Hayes
compatible modem, through user interface port 548. Once
communications are established, main CPU 332 operates as if were
connected to a local computer and operates as a slave on user
interface port 548, responding to commands issued.
[0107] Communications to service engineers, maintenance centers,
and so forth are accomplished through maintenance interface port
550. Main CPU 332 initializes the communications to any hardware
attached to power controller logic 530 for maintenance interface
port 550. In one implementation, at power up, the initial baud rate
will be selected to 19200 baud, 8 data bits, 1 stop, and no parity.
The user has the ability to adjust and save the communications rate
setting via user port 548 or optional smart external display 542.
The saved communications rate is used the next time power
controller logic 530 is powered on. Main CPU 332 communicates with
a modem, such as a Hayes compatible modem, through maintenance
interface port 550. Once communications are established, main CPU
332 operates as if it were connected to a local computer and
operates as a slave on maintenance interface port 550, responding
to commands issued.
[0108] Still referring to FIG. 11, main CPU 332 orchestrates
operation for motor/generator, output power converters, and turbine
engine controls for power controller logic 530. The main CPU 332
does not directly perform motor/generator and output power
converter controls. Rather, motor/generator and output SP
processors 534 and 536 perform the specific control algorithms
based on data communicated from main CPU 332. Engine controls are
performed directly by main CPU 332 (see FIG. 16).
[0109] Main CPU 332 issues commands via SPI communications bus 538
to motor/generator SP 534 to execute the required motor/generator
control functions. Motor/generator SP 534 will operate
motor/generator 10 in either a DC bus voltage mode or a RPM mode as
selected by main CPU 332. In the DC bus voltage mode,
motor/generator SP 534 uses power from the motor/generator 10 to
maintain the DC bus voltage at the setpoint. In the RPM mode,
motor/generator SP 534 uses power from the motor/generator 10 to
maintain the engine speed of turbine engine 448 at the setpoint.
Main CPU 332 provides Setpoint values.
[0110] Main CPU 332 issues commands via SPI communications bus 538
to output SP 536 to execute required power converter control
functions. Output SP 536 will operate the output converter 374,
shown in FIG. 7, in a DC bus voltage mode, output current mode, or
output voltage mode as selected by main CPU 332. In the DC bus
voltage mode, output SP 536 regulates the vehicle drive system
power provided by output converter 374 to maintain the voltage of
DC bus 324 at the setpoint.
[0111] In the output current mode, output SP 536 uses power from
the DC bus 324 to provide commanded current out of the output
converter 374 for vehicle drive system 360. In the output voltage
mode, output SP 536 uses power from the DC bus 324 to provide
commanded voltage out of the output converter 374 for vehicle drive
system 360. Main CPU 332 provides Setpoint values.
[0112] Referring to FIGS. 12-14, control loops 560, 582 and 600 may
be used to regulate engine controls of turbine engine 448. These
loops include exhaust gas temperature (ECT) control (FIG. 12),
speed control (FIG. 13) and power control (FIG. 14). All three of
the control loops 560, 582 and 600 may be used individually and
collectively by main CPU 332 to provide the dynamic control and
performance required by power controller logic 530. One or more of
control loops 560, 582 and 600 may be joined together for different
modes of operation.
[0113] The open-loop light off control algorithm is a programmed
command of the fuel device, such as fuel control system 342, used
to inject fuel until combustion begins. In one configuration, main
CPU 332 takes a snap shot of the engine EGT and begins commanding
the fuel device from about 0% to 25% of full command over about 5
seconds. Engine light is declared when the engine EGT rises about
28.degree. C. (50.degree. F.) from the initial snap shot.
[0114] Referring to FIG. 12, EGT control loop 560 provides various
fuel output commands to regulate the temperature of the turbine
engine 448. Engine speed signal 562 is used to determine the
maximum EGT setpoint temperature 566 in accordance with
predetermined setpoint temperature values illustrated in EGT vs.
Speed Curve 564. EGT setpoint temperature 566 is compared by
comparator 568 against feedback EGT signal 570 to determine EGT
error signal 572, which is then applied to a proportional-integral
(PI) algorithm 574 for determining the fuel command 576 required to
regulate EGT at the setpoint. Maximum/minimum fuel limits 578 are
used to limit EGT control algorithm fuel command output 576 to
protect from integrator windup. Resultant EGT fuel output signal
580 is the regulated EGT signal fuel flow command. In operation,
EGT control mode loop 560 operates at about a 100 ms rate.
[0115] Referring to FIG. 13, speed control mode loop 582 provides
various fuel output commands to regulate the rotating speed of the
turbine engine 448. Feedback speed signal 588 is read and compared
by comparator 586 against setpoint speed signal 584 to determine
error signal 590, which is then applied to PI algorithm 592 to
determine the fuel command required to regulate turbine engine
speed at the setpoint. EGT control (FIG. 12) and maximum/minimum
fuel limits 596 are used in conjunction with the speed control
algorithm 582 to protect output signal 594 from surge and flame out
conditions. Resultant output signal 598 is regulated turbine speed
fuel flow command. In one implementation, speed control mode loop
582 operates at about a 20 ms rate.
[0116] Referring to FIG. 14, power control loop 600 regulates the
power producing potential of turbogenerator 358. Feedback power
signal 606 is read and compared by comparator 604 against setpoint
power signal 602 to determine power error signal 608, which is then
applied to PI algorithm 610 to determine the speed command required
to regulate output power at the setpoint. Maximum/minimum speed
limits 614 are used to limit the power control algorithm speed
command output to protect output signal 612 from running into over
speed and under speed conditions. Resultant output signal 616 is
regulated power signal turbine speed command. In one
implementation, the maximum operating speed of the turbine engine
is generally 96,000 RPM and the minimum operating speed of the
turbine is generally 45,000 RPM. The loop operates generally at
about a 500 ms rate.
[0117] Referring to FIG. 16, the electrical system SP and power
converter 770, attached to DC bus 324, regulates power to one or
more vehicle electrical systems, according to one embodiment.
Moreover, a battery source in vehicle drive system 360, such as
traction battery 1050 in FIG. 21, may be used as a start battery.
In the DC bus voltage control mode, traction battery 1050 provides
energy to regulate voltage on DC bus 324 to the bus voltage
setpoint command. Main CPU 332 commands the bus voltage on DC bus
324 to control at different voltage setpoint values depending on
the configuration of power controller 310. In the state of charge
(SOC) control mode, the traction battery is recharged.
[0118] In the various operating modes, power controller 310 will
have different control algorithms responsible for managing the DC
bus voltage level. Any of the options in SPs 534 and 536, have
modes that control power flow to regulate the voltage level of DC
bus 324. Under any operating circumstances, only one device is
commanded to a mode that regulates DC bus 324. Multiple algorithms
would require sharing logic that would inevitably make system
response slower and software more difficult to comprehend.
[0119] Referring now also to FIG. 15, state diagram 620 showing
various operating states of power controller 310 is illustrated.
Sequencing the system through the entire operating procedure
requires power controller 310 to transition through the operating
states defined in TABLE 1.
1TABLE 1 STATE SYSTEM # STATE DESCRIPTION 622 Power Up. Performs
activities of initializing and testing the system. Upon passing
Power On Self Test (POST), move to Standby state 624. 624 Stand By.
Closes power to bus and continues system monitoring while waiting
for a start command. Upon receipt of Start Command, move to Prepare
to Start state 626. 626 Prepare to Start. Initializes any external
devices preparing for the start procedure. Returns to Stand By
state 624 if Stop Command received. Moves to Shut Down state 630 if
systems do not respond or if a fault is detected with a system
severity level (SSL) greater than 2. Upon systems ready, move to
Bearing Lift Off state 628. 628 Bearing Lift Off. Configures the
system and commands turbine engine 448 to be rotated to a
predetermined RPM, such as 25,000 RPM. Moves to Shut Down state 630
upon failure of turbine engine 448 to rotate, or receipt of a Stop
Command. Upon capture of rotor in motor/generator 10, moves to Open
Loop Light Off state 640. 640 Open Loop Light Off. Turns on
ignition system and commands fuel open loop to light turbine engine
448. Moves to Cool Down state 632 upon failure to light. Upon
turbine engine 448 light off, moves to Closed Loop Acceleration
state 642. 642 Closed Loop Acceleration. Continues motoring turbine
engine 448 using closed loop fuel control until the turbogenerator
system 200 reaches a predetermined RPM, designated as the No Load
state. Moves to Cool Down state 632 upon receipt of Stop Command or
if a fault occurs with a SSL greater than 2. Upon reaching No Load
state, moves to Run state 644. 644 Run. Turbine engine 448 operates
in a no load, self-sustaining state producing power to operate the
power controller 310. Moves to Warm Down state 648 if SSL is
greater than or equal to 4. Moves to Re-Charge state 634 if Stop
Command is received or if a fault occurs with a SSL greater than 2.
Upon receipt of Power Enable command, moves to Load state 646. 646
Load. Converter output contactor 510 is closed and turbogenerator
system 200 is producing power applied to vehicle drive system 360.
Moves to Warm Down state 648 if a fault occurs with a SSL greater
or equal to 4. Moves to Run state 644 if Power Disable command is
received. Moves to Re-Charge state 634 if Stop Command is received
or if a fault occurs with a SSL greater than 2. 634 Re-Charge.
System operates off of fuel only and produces power for recharging
an energy storage device if installed, such as traction battery
1050 shown in FIG. 21. Moves to Cool Down state 622 when energy
storage device is fully charged or if a fault occurs with a SSL
greater than 2. Moves to Warm Down state if a fault occurs with a
SSL greater than or equal to 4. 632 Cool Down. Motor/Generator 10
is motoring turbine engine 448 to reduce EGT before moving to Shut
Down state 630. Moves to Re-Start state 650 if Start Command
received. Upon expiration of Cool Down Timer, moves to Shut Down
state 630 when EGT is less than or equal to 500.degree. F. 650
Re-Start. Reduces speed of turbine engine 448 to begin open loop
light off when a Start Command is received in the Cool Down state
632. Moves to Cool Down state 632 if Stop Command is received or if
a fault occurs with a SSL greater than 2. Upon reaching RPM less
than or equal to 25,000 RPM, moves to Open Loop Light Off state
640. 638 Re-Light. Performs a re-light of turbine engine 448 during
transition from the Warm Down state 648 to Cool Down state 632.
Allows continued engine cooling when motoring is no longer
possible. Moves to Cool Down state 632 if a fault occurs with a SSL
greater than or equal to 4. Moves to Fault state 635 if turbine
engine 448 fails to light. Upon light off of turbine engine 448,
moves to Closed Loop Acceleration state 642. 648 Warm Down.
Sustains operation of turbine engine 448 with fuel at a
predetermined RPM, such as 50,000 RPM, to cool turbine engine 448
when motoring of turbine engine 448 by motor/ generator 10 is not
possible. Moves to Fault state 635 if EGT is not less than
650.degree. F. within a predetermined time. Upon achieving an EGT
less than 650.degree. F., moves to Shut Down state 630. 630
Shutdown. Reconfigures turbogenerator system 200 after a cooldown
in Cool Down state 632 or Warm Down state 648 to enter the Stand By
state 624. Moves to Fault state 635 if a fault occurs with a SSL
greater than or equal to 4. Moves to Stand By state 624 when RPM is
less than or equal to zero. 635 Fault. Turns off all outputs when a
fault occurs with a SSL equal to 5 indicating that the presence of
a fault which disables power conversion exists. Logic power is
still available for interrogating system faults. Moves to Stand By
state 624 upon receipt of System Reset. 636 Disable. Fault has
occurred where processing may no longer be possible. All system
operation is disabled when a fault occurs with a SSL equal to
6.
[0120] Main CPU 332 begins execution in Power Up state 622 after
power is applied. Transition to Stand By state 624 is performed
upon successfully completing the tasks of Power Up state 622.
Initiating a start cycle transitions the system to Prepare to Start
state 626 where all system components are initialized for an engine
start of turbine engine 448. The turbine engine 448 then sequences
through start states including Bearing Lift Off state 628, Open
Loop Light Off state 640 and Closed Loop Acceleration state 642 and
moves on to the "run/load" states, Run state 644 and Load state
646.
[0121] To shutdown the system, a stop command which sends the
system into either Warm Down state 648 or Cool Down state 632 is
initiated. Systems that have a battery may enter Re-Charge state
634 prior to entering Warm Down state 648 or Cool Down state 632.
When the system has finally completed the "warm down" or "cool
down" process in Warm Down state 648 or Cool Down state 632, a
transition through Shut Down state 630 will be made before the
system re-enters Stand By state 624 awaiting the next start cycle.
During any state, detection of a fault with a system severity level
(SSL) equal to 5, indicating that the system should not be
operated, will transition the system state to Fault state 635.
Detection of faults with an SSL equal to 6 indicate a processor
failure has occurred and will transition the system to Disable
state 636.
[0122] In order to accommodate each mode of operation, the state
diagram is multidimensional to provide a unique state for each
operating mode. For example, in Prepare to Start state 626, control
requirements will vary depending on the selected operating
mode.
[0123] Each combination is known as a system configuration (SYSCON)
sequence. Main CPU 332 identifies each of the different system
configuration sequences in a 16-bit word known as a SYSCON word,
which is a bit-wise construction of an operating mode and system
state number. In one configuration, the system state number is
packed in bits 0 through 11. The operating mode number is packed in
bits 12 through 15. This packing method provides the system with
the capability of sequence through 4096 different system states in
16 different operating modes.
[0124] Separate Power Up states 622, Re-Light states 638, Warm Down
states 648, Fault states 635 and Disable states 636 may not be
required for each mode of operation. The contents of these states
are mode independent.
[0125] Power Up state 622 Operation of the system begins in Power
Up state 622 once application of power activates main CPU 332. Once
power is applied to power controller 310, all the hardware
components will be automatically reset by hardware circuitry. Main
CPU 332 is responsible for ensuring the hardware is functioning
correctly and configuring the components for operation. Main CPU
332 also initializes its own internal data structures and begins
execution by starting the Real-Time Operating System (RTOS).
Successful completion of these tasks directs transition of the
software to Stand By state 624. Main CPU 332 performs these
procedures in the following order:
[0126] 1. Initialize main CPU 332
[0127] 2. Perform RAM Test
[0128] 3. Perform FLASH Checksum
[0129] 4. Start RTOS
[0130] 5. Run Remaining POST
[0131] 6. Initialize SPI Communications
[0132] 7. Verify Motor/Generator SP Checksum
[0133] 8. Verify Output SP Checksum
[0134] 9. Initialize IntraController Communications
[0135] 10. Resolve External Device Addresses
[0136] 11. Look at Input Line Voltage
[0137] 12. Determine Mode
[0138] 13. Initialize Maintenance Port
[0139] 14. Initialize User Port
[0140] 15. Initialize External Option Port
[0141] 16. Initialize InterController
[0142] 17. Chose Master/Co-Master
[0143] 18. Resolve Addressing
[0144] 19. Transition to Stand By State (depends on operating
mode)
[0145] Stand By state 624 Main CPU 332 continues to perform normal
system monitoring in Stand By state 624 while it waits for a start
command signal. Main CPU 332 commands an energy source in vehicle
drive system 360, such as traction battery 1050, to provide
continuous power supply. In operation, main CPU 332 will often be
left powered on waiting to be started or for troubleshooting
purposes. While main CPU 332 is powered up, the software continues
to monitor the system and perform diagnostics in case any failures
should occur. All communications will continue to operate providing
interface to external sources. A start command will transition the
system to the Prepared to Start state 626.
[0146] Prepared to Start state 626 Main CPU 332 prepares the
control system components for turbine engine 448 start process.
Many external devices may require additional time for hardware
initialization before the actual start procedure can commence. The
Prepared to Start state 626 provides those devices the necessary
time to perform initialization and send acknowledgment to main CPU
332 that the start process can begin. Once all systems are ready to
go, the software will transition to the Bearing Lift Off state
628.
[0147] Bearing Lift Off state 628 Main CPU 332 commands
motor/generator SP and power converter 456 to motor the turbine
engine 448 from typically about 0 to 25,000 RPM to accomplish the
bearing lift off procedure. A check is performed to ensure the
shaft of turbine engine 448 is rotating before transition to the
next state occurs.
[0148] Open Loop Light Off state 640 Once the motor/generator 10
reaches its liftoff speed, the software commences and ensures
combustion is occurring in the turbine engine 448. In one
configuration, main CPU 332 commands motor/generator SP and power
converter 314 to motor the turbine engine 448 to a dwell speed of
about 25,000 RPM. Execution of Open Loop Light Off state 640 starts
combustion. Main CPU 332 then verifies that turbine engine 448 has
not met the "fail to light" criteria before transition to the
Closed Loop Acceleration state 642.
[0149] Closed Loop Acceleration state 642 Main CPU 332 sequences
turbine engine 448 through a combustion heating process to bring
turbine engine 448 to a self-sustaining operating point. In one
configuration, commands are provided to motor/generator SP and
power converter 314 commanding an increase in turbine engine speed
to about 45,000 RPM at a rate of about 4000 RPM/sec. Fuel controls
of fuel supply system 342 are executed to provide combustion and
engine heating. When turbine engine 448 reaches "no load" (requires
no electrical power to motor), the software transitions to Run
state 644.
[0150] Run state 644 Main CPU 332 continues operation of control
algorithms to operate turbine engine 448 at no load. Power may be
produced from turbine engine 448 for operating control electronics
and recharging any energy storage device, such as traction battery
1050, in vehicle drive system 360. No power is output to the motor
1054 of the vehicle drive system 360, as shown in FIG. 21. A power
enable signal transitions the software into Load state 646. A stop
command transitions the system to begin shutdown procedures (may
vary depending on operating mode).
[0151] Load state 646 Main CPU 332 continues operation of control
algorithms to operate turbogenerator 358 at the desired load. Load
commands are issued through the communications ports, display or
system loads. A stop command transitions main CPU 332 to begin
shutdown procedures (may vary depending on operating mode). A power
disable signal can transition main CPU 332 back to Run state
644.
[0152] Re-charge state 634 Systems that have an energy storage
option may be required to charge the energy storage device, such as
traction battery 1050, in vehicle drive system 360 to maximum
capacity before entering Warm Down state 648 or Cool Down state
632. During Recharge state 634, main CPU 332 continues operation of
the turbogenerator 358 producing power for battery charging and
power controller 310. No output power is provided. When traction
battery 1050 has been charged, the system transitions to either
Cool Down state 632 or Warm Down state 648, depending on system
fault conditions.
[0153] Cool Down state 632 Cool Down state 632 provides the ability
to cool the turbine engine 448 after operation and a means of
purging fuel from the combustor. After normal operation, software
sequences the system into Cool Down state 632. In one
configuration, turbine engine 448 is motored to a cool down speed
of about 45,000 RPM Airflow continues to move through turbine
engine 448 preventing hot air from migrating to mechanical
components in the cold section. This motoring process continues
until the turbine engine EGT falls below a cool down temperature of
about 193.degree. C. (380.degree. F.). Cool Down state 632 may be
entered at much lower than the final cool down temperature when
turbine engine 448 fails to light. The engine's combustor of
turbine engine 448 requires purging of excess fuel which may
remain. The software operates the cool down cycle for a minimum
purge time of 60 seconds. This purge time ensures remaining fuel is
evacuated from the combustor. Completion of this process
transitions the system into Shut Down state 630. For user
convenience, the system does not require a completion of the entire
Cool Down state 632 before being able to attempt a restart. Issuing
a start command transitions the system into Restart state 650.
[0154] Restart state 650 In Restart state 650, turbine engine 448
is configured from Cool Down state 632 before turbine engine 448
can be restarted. In one configuration, the software lowers the
speed of turbine engine 448 to about 25,000 RPM at a rate of 4,000
RPM/sec. Once the turbine engine speed has reached this level, the
software transitions the system into Open Loop Light Off state 640
to perform the actual engine start.
[0155] Shutdown state 630 During Shut Down state 630, the turbine
engine and motor/generator rotor shaft is brought to rest and
system outputs are configured for idle operation. In one
configuration, the software commands the rotor shaft to rest by
lowering the turbine engine speed at a rate of 2,000 RPM/sec or no
load condition, whichever is faster. Once the speed reaches about
14,000 RPM, the motor/generator SP and power converter 314 is
commanded to reduce the shaft speed to about 0 RPM in less than 1
second.
[0156] Re-light state 638 When a system fault occurs where no power
is provided from the traction battery, the software re-ignites
combustion to perform Warm Down state 648. The motor/generator SP
and power converter 314 is configured to regulate voltage (power)
for the internal DC bus. Fuel is added in accordance with the open
loop light off fuel control algorithm in Open Loop Light Off state
640 to ensure that combustion occurs. Detection of engine light
will transition the system to Warm Down state 648.
[0157] Warm Down state 648 Fuel is provided, when no electric power
is available to motor turbine engine 448 at a no load condition, to
lower the operating temperature in Warm Down state 648. In one
configuration, engine speed is operated at about 50,000 RPM by
supplying fuel through the speed control algorithm described above
with regard to FIG. 13. EGT temperatures of turbine engine 448 less
than about 343.degree. C. (650.degree. F.) causes the system to
transition to Shut Down state 630.
[0158] Fault state 635 The system disables all outputs placing the
system in a safe configuration when faults that prohibit safe
operation of the turbine system are present. Operation of system
monitoring and communications may continue if the energy is
available.
[0159] Disable State 636 The system disables all outputs placing
the system in a safe configuration when faults that prohibit safe
operation of the turbine system are present. System monitoring and
communications may not continue.
[0160] Referring to FIG. 16, motor/generator SP and power converter
314 and output SP and power converter 316 provide an interface for
energy source 312 and vehicle drive system 360, respectively, to DC
bus 324. For illustrative purposes, energy source 312 is
turbogenerator 358 including turbine engine 448 and motor/generator
10. Fuel control system 342 provides fuel via fuel line 476 to
turbine engine 448.
[0161] Motor/generator power converter 314, which may include
motor/generator SP 534 and motor/generator converter 372, and
output power converter 316, which may include output SP 536 and
output converter 374, operate as customized bi-directional,
switching power converters under the control of main CPU 332. In
particular, main CPU 332 reconfigures the motor/generator power
converter 314 and output power converter 316 into different
configurations to provide for the various modes of operation. In
one embodiment, these modes of operation include battery start and
vehicle drive system connect.
[0162] Power controller 310 controls the way in which
motor/generator 10 and vehicle drive system 360 sinks or sources
power, and DC bus 324 is regulated, at any time. Power converter
322, which may include electrical system SP and converter 770 and
electrical output 470, may be supplied with power from either the
traction battery 1050 within vehicle drive system 360 or
turbogenerator 358. Main CPU 332 provides command signals via line
779 to turbine engine 448 to determine the speed of turbogenerator
358. The speed of turbogenerator 358 is maintained through
motor/generator 10. Main CPU also provides command signals via fuel
control line 780 to fuel control system 342 to maintain the EGT of
turbine engine 448 at its maximum efficiency point. Motor/generator
SP 534, operating motor/generator converter 372, is responsible for
maintaining the speed of turbogenerator 358, by putting current
into or pulling current out of motor/generator 10.
[0163] Referring to FIG. 16 and FIG. 21, in the battery start mode,
the traction battery 1050 in the vehicle drive system 360 is
provided for starting purposes while energy source 312, such as
turbine engine 448 and motor/generator 10, may supply transient and
steady state energy. In the vehicle drive system connect mode, the
energy source 312, in this example turbogenerator 358 including
turbine engine 448 and motor/generator 10, is connected to the
vehicle drive system 360 providing load leveling and management.
The system operates as a current source, pumping current into
vehicle drive system 360. In both modes, the DC/DC converter 322
may be configured to provide electrical power on power lines
320.
[0164] Multi-pack Operation The power controller can operate in a
single or multi-pack configuration. In particular, power controller
310, in addition to being a controller for a single turbogenerator,
is capable of sequencing multiple turbogenerator systems as well.
Referring to FIG. 17, for illustrative purposes, multi-pack system
810 including three power controllers 818, 820 and 822 is shown.
The ability to independently control multiple power controllers
818, 820 and 822 is made possible through digital communications
interface and control logic contained in each controller's main CPU
(not shown).
[0165] Two communications busses 830 and 834 are used to create the
intercontroller digital communications interface for multi-pack
operation. One bus 834 is used for slower data exchange while the
other bus 830 generates synchronization packets at a faster rate.
In a typical implementation, for example, an IEEE-502.3 bus links
each of the controllers 818, 820 and 822 together for slower
communications including data acquisition, start, stop, power
demand and mode selection functionality. An RS485 bus links each of
the systems together providing synchronization of the output power
waveforms.
[0166] The number of power controllers that can be connected
together is not limited to three, but rather any number of
controllers can be connected together in a multi-pack
configuration. Distribution panel 832, typically comprised of
circuit breakers, provides for distribution of energy.
[0167] Multi-pack control logic determines at power up that one
controller is the master and the other controllers become slave
devices. The master is in charge of handling all user-input
commands, initiating all inter-system communications transactions,
and dispatching units. While all controllers 818, 820 and 822
contain the functionality to be a master, to alleviate control and
bus contention, one controller is designated as the master.
[0168] At power up, the individual controllers 818, 820 and 822
determine what external input devices they have connected. When a
controller contains a minimum number of input devices it sends a
transmission on intercontroller bus 830 claiming to be master. All
controllers 818, 820 and 822 claiming to be a master begin
resolving who should be master. Once a master is chosen, an address
resolution protocol is executed to assign addresses to each slave
system. After choosing the master and assigning slave addresses,
multi-pack system 810 can begin operating.
[0169] A co-master is also selected during the master and address
resolution cycle. The job of the co-master is to act like a slave
during normal operations. The co-master should receive a constant
transmission packet from the master indicating that the master is
still operating correctly. When this packet is not received within
a safe time period, 20 ms for example, the co-master may
immediately become the master and take over master control
responsibilities.
[0170] Logic in the master configures all slave turbogenerator
systems. A master controller, when selected, will communicate with
its output converter logic (output SP) that this system is a
master. The output SP is then responsible for transmitting packets
over the intercontroller bus 830, synchronizing the output
waveforms with all slave systems. Transmitted packets will include
at least the angle of the output waveform and error-checking
information with transmission expected every quarter cycle to one
cycle.
[0171] A minimum number of input devices are typically desired for
a system 810 to claim it is a master during the master resolution
process. Input devices that are looked for include a display panel,
an active RS232 connection and a power meter connected to the
option port.
[0172] The master control logic dispatches controllers based on
operating time. This would involve turning off controllers that
have been operating for long periods of time and turning on
controllers with less operating time, thereby reducing wear on
specific systems.
[0173] Referring now to FIG. 18, power controller 310 includes
brake resistor 912 connected across DC bus 324. Brake resistor 912
acts as a resistive load, absorbing energy when output converter
374 is turned off under the direction of output SP 536. In
operation, when output converter 374 is turned off, power is no
longer exchanged with vehicle drive system 360, but power is still
being received from motor/generator 10 within turbogenerator 358,
which power is then absorbed by brake resistor 912. The power
controller 310 detects the DC voltage on DC bus 324 between
motor/generator converter 372 and output converter 374. When the
voltage starts to rise, brake resistor 912 is turned on to allow it
to absorb energy.
[0174] In one configuration, motor/generator produces three phases
of AC at variable frequencies. Motor/generator converter 372, under
the control of motor/generator SP 534, converts the AC from
motor/generator 10 to DC which is then applied to DC bus 324
(regulated for example at 750 vDC) which is supported by capacitor
910 (for example, at 800 microfarads with two milliseconds of
energy storage). Output converter 374, under the control of output
SP 536, converts the DC on DC bus 324 into operating DC
voltage.
[0175] Current from DC bus 324 can by dissipated in brake resistor
912 via modulation of switch 914 operating under the control of
motor/generator SP 534. Switch 914 may be an IGBT switch, although
other conventional or newly developed switches may be utilized as
well.
[0176] Motor/generator SP 534 controls switch 914 in accordance to
the magnitude of the voltage on DC bus 324. When output converter
374 is turned off, it no longer is able to maintain the voltage of
DC bus 324, so power coming in from motor/generator 10 causes the
bus voltage of DC bus 324 to rise quickly. The rise in voltage is
detected by motor/generator SP 534, which turns on brake resistor
912 via switch 914 and modulates it on and off until the bus
voltage is restored to its desired voltage, for example, 750 VDC.
Brake resistor 912 is sized so that it can ride through the
transient and the time taken to restart output converter 374.
[0177] On detecting abnormal vehicle drive system behavior, a
vehicle drive system fault shutdown is initiated. When power
controller 310 initiates a vehicle drive system fault shutdown,
output contactor 510, shown in FIG. 10, is opened within a
predetermined period of time, for example, 100 msec, and fuel
cutoff solenoids 498 are closed, removing fuel from turbogenerator
358. A warm shutdown ensues during which control power is supplied
from motor/generator 10 as it slows down. In one configuration, the
warm-down lasts about 1-2 minutes before the rotor (not shown) is
stopped.
[0178] FIG. 19 schematically illustrates a hybrid electric vehicle
1010 according to one embodiment. FIG. 20 illustrates a block
diagram of the interplay between the power controller 310 and the
vehicle drive system 360. The hybrid electric vehicle 1010 employs
a turbine power unit to efficiently generate electric power for
driving the electric motor(s). The turbine power unit also supplies
electrical power to the electrical system and other components
within the vehicle. One or more traction batteries and/or other
energy storage devices may be used in combination with the turbine
power unit to provide instantaneous current, when necessary, to the
electric motor(s).
[0179] Referring to FIGS. 19 and 20, hybrid electric vehicle 1010
has a body 1012, a pair of front wheels 1014 and 1014', and a pair
of rear wheels 1016 and 1016'. At least one of the wheels is
drivingly connected to an electric motor. In the disclosed
embodiment, rear wheels 1016 and 1016' are connected to electric
motors 1054 and 1054' and the drive train 1020 and 1020',
respectively. Alternatively, or in addition thereto, front wheels
1014, 1014' can be driven individually or in combination with
driven rear wheels 1016 and 1016'. The hybrid electric vehicle 1010
includes a micro-turbine system such as turbogenerator 358 (see,
e.g., FIGS. 1A through 1E) and a power controller 310 (see, e.g.,
FIG. 3 and FIGS. 5-10). The turbogenerator 358, under control of
the power controller 310, generates AC power on signal line(s) 203
to drive the one or more electric motors 1054 and 1054'. In one or
more embodiments, the turbogenerator 358 provides between 3 to 30
kilowatts (kW) of power. A turbogenerator generating power greater
than 30 kWs may be readily used.
[0180] The AC/DC converter 314 of the power controller 310 converts
the AC power to DC power on DC bus 324. The DC voltage on the DC
bus 324 may be set to a voltage that is between 100 to 800 or more
volts. In one typical embodiment, the DC voltage on DC bus is set
to 750 volts. The DC/DC converter 316 of the power controller 310
converts the DC voltage on the DC bus 324 to an operating DC
voltage on output lines 1056. In one embodiment, the operating DC
voltage on the output lines 1056 may be set to a voltage that is
between 100 to 750 or more volts. In another embodiment, the
operating DC voltage on output lines is set to a voltage that is
between 250 to 400 VDC. The DC voltage on DC bus 324 and/or DC
operating voltage on output lines 1056 may be set at any user
defined voltage level(s).
[0181] A second DC/DC converter 322 of the power controller 310
converts the DC voltage on DC bus 324, which may be as high as 800
volts or higher, to, for example, 12 volts to power the electrical
system and other components of the vehicle 1010. The DC/DC
converter 322 may be located outside of the power controller
310.
[0182] A fuel source 1028, such as a gasoline tank, propane tank,
etc. stores fuel or hydrocarbon fuel, which is supplied to the
turbogenerator 358 under control of the power controller 310. The
turbogenerator 358 may be compatible with high pressure (e.g.,
greater than 52 pounds per square inch) natural gas, diesel fuels,
high-pressure gaseous propane, hydrogen, unleaded gasoline,
ethanol, methanol, ethane, methane, etc. In one embodiment, where
the turbogenerator 358 is compatible with burning diesel fuel, #2
diesel fuel, meeting the ASTM D975 Diesel Fuel Specifications, is
used. In this embodiment, the diesel fuel is delivered between a
minimum temperature of -4.degree. F. (-20.degree. C.) and a maximum
temperature of 160.degree. F. (72.degree. C.).
[0183] The output lines 1056 of the power controller 310 are
coupled to the vehicle drive system 360. The vehicle drive system
360 includes one or more energy storage devices 1050,
bi-directional drive control unit 1052, and one or more electric
motors 1054 and 1054'. In one embodiment, the energy storage
devices 1050 comprise one or more traction (or semi-traction)
batteries, including, but not limited or restricted to, lead-acid,
nickel-cadmium, nickel-metal hydride, sodium-sulphur, sodium-nickel
chloride, zinc-bromine, zinc-air, and lithium batteries. Other
energy storage devices including a flywheel, ultracap, etc. may be
coupled in parallel with the traction battery(ies).
[0184] The traction battery 1050 is coupled across output lines
1056 to act as a current source or current sink depending on system
configuration. The drive control unit 1052 is coupled between
output lines 1056 and the motors 1054 and 1054', and is controlled
by the power controller 310, to couple or isolate, as the case may
be, the DC operating voltage on output lines 1056 to the motor
1054. Although the vehicle drive system 360 may control more than
one motor, in another embodiment, a separate vehicle drive system
may be used for each motor.
[0185] The power controller 310 controls the turbogenerator 358
independent of the vehicle's power train controls and operates in
response to control or "demand" signals, such as START, STOP, POWER
LEVEL (acceleration), and BRAKE signals 1009 generated by a vehicle
operator 1019, to regulate the electric motors 1054 and 1054'. The
power controller 310 controls the motor torque by regulating a
delivery of fuel and air to the turbogenerator 358. In low-load
conditions, where the energy needed is less than the maximum
electrical power output of the turbogenerator 358, the electric
power needed by the motor 1054 is generated by the turbogenerator
358, under control of the power controller 310. When the vehicle's
power requirements exceed the output capacity of turbogenerator
358, or where instantaneous power, beyond that currently provided
by the turbogenerator, is needed (e.g., for acceleration, hill
climbs, sustained high speed cruising), the traction battery 1050
sources the additional current to the motor(s) as needed up to a
maximum sustainable power level.
[0186] Before the turbogenerator 358 is started, the traction
battery 1050 may be used to provide power to the electrical system
and other devices of the vehicle. This may be accomplished by the
power controller 310 by disabling the drive control unit 1052 to
isolate the motor(s) 1054 from the traction battery 1050, disabling
AC/DC converter 314 to isolate the motor/generator 10 from the DC
bus 324, configuring the DC/DC converter 316 to apply power from
the traction battery 1050 to the DC bus 324, and configuring the
DC/DC converter 322 to convert the DC voltage on DC bus 324 to an
appropriate voltage on electric output lines 320.
[0187] Once a START signal is detected, the power controller 310
uses the traction battery 1050 to start the motor/generator 10
(e.g., battery start mode). This is accomplished by disabling the
drive control unit 1052 to isolate the motor(s) 1054 from the
traction battery 1050, configuring the DC/DC converter 316 to apply
the DC power, supplied by the traction battery 1050, on output
lines 1056 to the DC bus 324, and configuring the AC/DC converter
314 to convert the DC power on DC bus 324 to AC power on signal
lines 203 to start motor/generator 10. Once sufficient current is
pumped into windings of motor/generator 10, where the
motor/generator reaches a self-sustaining operating point, the
power controller 310 reverses the direction of the AC/DC converter
314 to boost the motor/generator 10 output voltage and provide a
regulated DC bus voltage on DC bus 324.
[0188] Once a POWER DEMAND signal is detected, the power controller
310 configures the driver control unit 1052 to couple the operating
DC voltage on output lines 1056 to the motor 1054 and drive the
motor 1054. The turbogenerator 358 pumps current into the motor
1054 (e.g., vehicle drive system connect mode). As the POWER DEMAND
signal increases/decreases, the power controller 310
increases/decreases fuel flow into the turbogenerator 358 to
increase/decrease the power output of the turbogenerator 358 to
meet the current demand of the load. If the motor 1054 demands more
current than is then-available, the traction battery 1050 provides
instantaneous and sustained current to the load until the
turbogenerator 358 is able to supply, if possible, the additional
current at the new operating point.
[0189] The hybrid electric vehicle 1010 utilizes a regenerative
braking system to charge the traction battery 1050. When the
vehicle is braking, the motor 1054 acts as a generator, converting
kinetic energy at the wheels 1016, 1016' to potential energy, to
charge traction battery 1050. This is accomplished by reversing the
direction of drive control unit 1052 to allow the traction battery
1050 to draw power from the motor 1054. The traction battery 1050
may be recharged by simultaneously drawing power from the DC bus
324. The traction battery 1050 may also be recharged by the
turbogenerator 358 during an idle mode.
[0190] The hybrid electric vehicle 1010 further employs hot
shutdown protection (e.g., detection of a STOP signal) by cutting
fuel to the turbogenerator 358, turning on a break resistor, and
isolating the motor 1054 from the operating DC voltage on the
output lines 1056. The hybrid electric vehicle 1010 further
provides over-voltage protection in the event that the load is
abruptly removed. In such a situation, the power controller 310
senses the operating DC voltage on output lines 1056 and prevents
the operating DC voltage from exceeding the maximum operating DC
voltage by a predetermined amount (e.g., 10%).
[0191] In another embodiment, the hybrid electric vehicle 1010 may
use AC motors 1054 and 1054'. In this embodiment, a DC/AC converter
(not shown) is placed between the drive control unit 1052 and the
motors 1054 and 1054' to convert the DC operating voltage on output
lines 1056 to AC power (and optionally three-phase AC power).
[0192] In yet another embodiment, the hybrid electrical vehicle
1010 may include more than one turbine power unit. In such
embodiment, each turbine power unit (such as a turbogenerator) may
be coupled to the power controller 310 in parallel. The power
controller 310 may independently control each turbogenerator to
supply AC power, thereby increasing the current drive available for
driving motors 1054 and 1054'.
[0193] In one or more embodiments, to maximize turbogenerator
efficiency, which may be 92% or greater, the power controller 310
controls the turbogenerator to operate at a turbine exit
temperature of about 1100.degree. F. (593.degree. C.).
[0194] The power controller 1030 may be coupled to an interface,
such as user port 548 and/or maintenance port 550 (FIG. 11), for
connection to a computer, workstation, modem or other data terminal
equipment which allows remote communication for maintenance,
service, trouble shooting, performance monitoring, field upgrades,
etc. The interface allows remote START, STOP, POWER DEMAND, BRAKE,
adjustable variables, and fault reset input to the power controller
310.
[0195] Having now described the invention in accordance with the
requirements of the patent statutes, those skilled in this art will
understand how to make changes and modifications in the present
invention to meet their specific requirements or conditions. For
example, the power controller, while described generally, may be
implemented in an analog or digital configuration. In the preferred
digital configuration, one skilled in the art will recognize that
various terms utilized in the invention are generic to both analog
and digital configurations of power controller. For example,
converters referenced in the present application is a general term
which includes inverters, signal processors referenced in the
present application is a general term which includes digital signal
processors, and so forth. Correspondingly, in a digital
implementation of the present invention, inverters and digital
signal processors would be utilized. Such changes and modifications
may be made without departing from the scope and spirit of the
invention as set forth in the following claims.
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